1. Field of the Invention
This invention generally relates to a heavy-duty, time-delay current-limiting fuse and, more particularly, to a fuse capable of reliably handling electrical currents in such amperage ranges as 61 to 100 amps., 101 to 200 amps., 201 to 400 amps. and 401 to 600 amps.
2. Description of the Prior Art
Heavy-duty current-limiting fuses are well known in the art for conducting electrical currents in predetermined safety amperage ranges along an electrical circuit, and for interrupting the electrical circuit in an overload condition when the electrical current exceeds the safety range. Typically, such a heavy-duty fuse consisted of a cartridge in which one elongated element was slidably received at least partially within and on another elongated element. The two elements were eutectically soldered together along at least a portion of their lengths, and were respectively connected to a pair of fusible links which, in an overload condition, generated sufficient heat to melt the solder after a time delay. When the solder melted, a spring was released to urge the two elements lengthwise apart from each other.
Although generally satisfactory for their intended purpose, the prior art fuses were not altogether reliable in operation because the elements in certain instances had a tendency to restrike, i.e. to again electrically contact each other and conduct the electrical current therethrough along the electrical circuit. In addition, after the solder melted, the spring moved the two elements only slightly apart lengthwise. Where high amperage currents were involved, this slight spacing between the elements sometimes was insufficient to prevent arcing between the elements. The prior art fuses also required a time-consuming and painstaking assembly procedure.